A control of amounts of biological components in blood, such as blood glucose (blood sugar) and blood cholesterol, is important to prevent and treat various diseases, such as diabetes and hyperlipidemia. However, to measure amounts of biological components in blood, a small amount of blood usually needs to be drawn, which is painful for an individual. Blood drawing also requires troublesome tasks, such as sterilization of the blood drawing area and proper treatment of consumables, so that frequent blood drawing for the measurement of amounts of biological components for preventive reasons or other purposes is apt to be averted.
To address this problem, a non-invasive measurement device which measures amounts of biological components without drawing blood has been proposed (Patent Literature 1). In this device, light is cast onto a biological tested area and the spectral characteristics of light (object light) emitted from biological components inside the tested area in response to the cast light is analyzed to identify the biological component. Specifically, object light, including transmitted light and diffused/scattered light, generated from each of the bright points which optically form biological components is guided through an objective lens to a phase shifter composed of a fixed mirror unit and a movable mirror unit, and object beams reflected from the two mirror units are made to interfere with each other on an imaging plane. The movable mirror unit is moved by a piezo element or the like, and a phase difference corresponding to the moving distance of the movable mirror unit is given to the object beams reflected from the fixed mirror unit and the movable mirror unit. The intensity of the interference light produced from the two beams changes with their phase difference, forming a so-called interferogram. This interferogram is Fourier-transformed to obtain spectral characteristics (spectrum) of the object light.